Building a Clock – From Design to Not-Quite-Working Prototype

Most of the projects I post here are in some state of functionality, but this mechanical clock I’ve been working on is a very large project, so here’s where I am in the build.  I’ve taken several videos of my progress, but I thought I’d start with the escapement first, since to me it’s the most interesting single mechanism in a clock.

As noted, I really thought it would be the most difficult part, but after laying everything out on the AutoCAD-like Draftsight (my review for Windows or Ubuntu), it turned out pretty well.  The difficult part is turning out to be the gears.

Tmechanical-clock-cadhe original clock CAD design, as seen in the sketch to the right, has the gears setup to act as their own hands.  The second “hand” is to be the purple-ish gear to the right.  This is then gear-reduced by a factor of 3600 (seconds per hour) to make the top-middle green gear the minute “hand.”  The leftmost gear is then geared by a factor of 12 to act as the hour hand.  In theory this should be really easy.

In reality though, there are still a few issues to work out.  I’ll let the next videos do most of the talking, but they mostly stem from the pulley and escapement pendulum interfering with each other, and my fear of the pulley being too far from the base board.  I also seriously oversimplified the gear design.  Going through this process, I have more and more respect for the engineers that worked in the era before computer aided design and PLCs to take care of the timing and clearance issues.

Hopefully I won’t have to remake the gears, but it’s possible.  I love seeing things come together, but I suppose it’s the process that’s really enjoyable (and frustrating).  Like that video game I just had to beat when I was younger – as in a few month ago – you both love and hate these kinds of challenges.  I think I’ve got a decent design, and considering I just started my clock-making “career” a few weeks ago, it seems like things are off to a good start.

The next video deals with some of my thoughts before assembling the gears and planning how the escapement would work.  The second, and final, video is a time-lapse of my trusty Zen Toolworks CNC router cutting out the escapement gear.  The video didn’t turn out that well, so I give you permission to skip it if you’ve read this far.  I should also note that I was able to get the backplate onto my little Zen Toolworks 7×12 router to get the holes internally cut.  It was helpful to have the little clamps that I talk about here.

So a lot of information (and videos) in this one.  As for the gears, I might have had better luck using’s gear template generator.  I’ve actually got the PC version that can output DXFs, so not much of an excuse there!  Be sure to subscribe towards the upper-right of this page or follow via Twitter to see what comes next!